Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 590 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the ironing time (d) the same paper
2. 2.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a battery cell (c) lemon juice (d) an adult with an iron
4. 4.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
6. 6.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) ironing the paper (d) plugging in the iron
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the same cotton bud (d) the kind of juice
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
9. 9.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) letting the paper dry (d) dipping the cotton bud
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the ironing time
12. 12.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) lemon juice (d) a small bowl
16. 16.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
17. 17.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) reading the message
18. 18.🍋 Which of these steps is a job a child can do? (a) writing the message (b) putting the iron away (c) plugging in the iron (d) cutting the lemon
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same cotton bud (c) the kind of juice
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
21. 21.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
23. 23.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
24. 24.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a balloon (d) white paper
26. 26.True or false: writing the message is a job a child can do. (a) True (b) False
27. 27.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) letting the paper dry (d) ironing the paper
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) turmeric powder (d) white paper
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
30. 30.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) musical (d) physical
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
32. 32.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a small bowl (d) yeast
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) turmeric powder (d) lemon juice
35. 35.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
36. 36.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
37. 37.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
38. 38.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
39. 39.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) white paper (c) a mirror (d) a magnet
40. 40.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) blue (d) green

Free science experiments lessons, practice and worksheets at talentjr.in/science-experiments-for-kids