Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 62 · 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 is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
2. 2.⚖️ 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) the same cotton bud (c) the kind of juice (d) the same paper
3. 3.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
4. 4.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
6. 6.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
7. 7.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it can burn skin (d) it is sticky
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) yeast (d) a small bowl
12. 12.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
13. 13.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same cotton bud (c) how dark the writing is (d) the same paper
15. 15.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
17. 17.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
18. 18.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
19. 19.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) letting the paper dry (d) plugging in the iron
20. 20.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) blue (d) green
23. 23.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
24. 24.True or false: putting the iron away is a job a child can do. (a) False (b) True
25. 25.⚖️ 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 change it (c) we measure it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) white paper (d) a balloon
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
29. 29.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
30. 30.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
31. 31.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
32. 32.True or false: ironing the paper is a job a child can do. (a) False (b) True
33. 33.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
34. 34.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) a mirror (d) lemon juice
38. 38.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) writing the message
39. 39.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) ironing the paper (d) letting the paper dry
40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it

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