Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 365 · 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.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
2. 2.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) physical (d) musical
3. 3.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a battery cell (c) a magnet (d) turmeric powder
4. 4.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
5. 5.⚖️ 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 change it (c) we measure it
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
7. 7.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
8. 8.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same cotton bud (d) the same paper
11. 11.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
12. 12.⚖️ 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
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) a small bowl (d) an adult with an iron
14. 14.True or false: ironing the paper is a job a child can do. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) a cotton bud (d) white paper
18. 18.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) plugging in the iron (d) letting the paper dry
19. 19.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
21. 21.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
24. 24.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
25. 25.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
27. 27.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
28. 28.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a battery cell (d) a mirror
30. 30.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.⚖️ 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
34. 34.⚖️ 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 same cotton bud
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
36. 36.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
37. 37.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
38. 38.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
39. 39.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) lemon juice (d) white paper

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