Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 965 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
2. 2.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
4. 4.⚖️ 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
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a small bowl (d) a magnet
6. 6.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) turmeric powder (c) a mirror (d) a magnet
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
8. 8.True or false: putting the iron away is a job a child can do. (a) True (b) False
9. 9.True or false: letting the paper dry is a job a child can do. (a) False (b) True
10. 10.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
11. 11.True or false: writing the message is a job a child can do. (a) True (b) False
12. 12.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
13. 13.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) putting the iron away
14. 14.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
15. 15.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
16. 16.⚖️ 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) False (b) True
17. 17.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
18. 18.⚖️ 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 paper
19. 19.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) a balloon (d) a mirror
21. 21.⚖️ 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
22. 22.⚖️ 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 change it (c) we keep it the same
23. 23.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a mirror (c) white paper (d) a balloon
24. 24.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the ironing time (c) the kind of juice (d) the same paper
26. 26.⚖️ 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
27. 27.🛟 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
28. 28.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) a rainbow (c) almost nothing (d) blue words
29. 29.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) writing the message
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
32. 32.True or false: writing the message is a job for an adult. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
34. 34.⚖️ 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 ironing time (c) how dark the writing is (d) the same cotton bud
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) white paper (c) a cotton bud (d) lemon juice
36. 36.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
37. 37.True or false: cutting the lemon is a job for an adult. (a) False (b) True
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) lemon juice (d) white paper
39. 39.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it

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