Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 413 · 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 steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) reading the message (d) ironing the paper
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) turmeric powder (d) a mirror
4. 4.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
5. 5.True or false: writing the message is a job for an adult. (a) True (b) False
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) an adult with an iron
10. 10.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) ironing the paper (d) plugging in the iron
12. 12.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
13. 13.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a cotton bud (d) an adult with an iron
15. 15.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
16. 16.True or false: putting the iron away is a job a child can do. (a) False (b) True
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) a cotton bud (d) lemon juice
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) turmeric powder (c) lemon juice (d) a cotton bud
20. 20.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) lemon juice (d) a magnet
22. 22.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
23. 23.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
24. 24.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
26. 26.True or false: reading the message is a job a child can do. (a) True (b) False
27. 27.⚖️ 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 paper (c) how dark the writing is (d) the same cotton bud
28. 28.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
29. 29.⚖️ 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 kind of juice (c) how dark the writing is (d) the iron setting
30. 30.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) white paper (d) turmeric powder
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
33. 33.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
34. 34.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
35. 35.True or false: letting the paper dry is a job for an adult. (a) True (b) False
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
37. 37.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
38. 38.True or false: plugging in the iron is a job a child can do. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a cotton bud (d) a balloon
40. 40.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a mirror (c) yeast (d) turmeric powder

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