Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 625 · 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? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
2. 2.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) reading the message
3. 3.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) cutting the lemon (d) reading the message
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) an adult with an iron (d) a cotton bud
5. 5.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
6. 6.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
7. 7.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) any child (d) only an adult
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
10. 10.True or false: cutting the lemon is a job a child can do. (a) False (b) True
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
12. 12.⚖️ 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) False (b) True
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
14. 14.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ 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
16. 16.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) how dark the writing is (d) the ironing time
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
20. 20.🍋 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
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
22. 22.⚖️ 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
23. 23.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) a balloon (d) a cotton bud
25. 25.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
26. 26.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
27. 27.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
28. 28.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
30. 30.⚖️ 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 change it (c) we keep it the same
31. 31.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) plugging in the iron
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
33. 33.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) ironing the paper
34. 34.⚖️ 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 ironing time
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same cotton bud
37. 37.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) writing the message
38. 38.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
39. 39.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) a battery cell (d) an adult with an iron
40. 40.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow

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