Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 538 · 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.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a magnet (d) a mirror
2. 2.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
4. 4.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) a cotton bud
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
9. 9.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
10. 10.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
11. 11.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
12. 12.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
13. 13.🔮 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
14. 14.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) a battery cell (d) a balloon
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
16. 16.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the iron setting (d) the kind of juice
18. 18.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) reading the message (d) writing the message
19. 19.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) a rainbow (d) almost nothing
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the same paper
22. 22.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) reading the message (d) writing the message
23. 23.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) white paper (c) a small bowl (d) an adult with an iron
24. 24.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) ironing the paper
25. 25.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
26. 26.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
27. 27.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, in the dark (c) no, it stays brown (d) yes, if shaken
28. 28.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
29. 29.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
30. 30.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
31. 31.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
32. 32.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
33. 33.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a cotton bud (d) a mirror
34. 34.🔍 Which is the odd one out? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) a cotton bud (d) an adult with an iron
36. 36.⚖️ 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 measure it (c) we change it
37. 37.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) turmeric powder (c) white paper (d) a cotton bud
40. 40.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed

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