Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 109 · 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.True or false: ironing the paper is a job for an adult. (a) False (b) True
2. 2.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
3. 3.True or false: white paper is needed for the secret lemon message. (a) True (b) False
4. 4.🍋 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) dipping the cotton bud
5. 5.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a magnet (d) lemon juice
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a balloon (c) a cotton bud (d) a small bowl
8. 8.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is magnetic (d) it is cold
9. 9.⚖️ 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) the kind of juice (d) how dark the writing is
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a cotton bud (c) a magnet (d) lemon juice
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
12. 12.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
14. 14.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) reading the message (d) letting the paper dry
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) blue words (d) a rainbow
17. 17.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
18. 18.⚖️ 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
19. 19.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
20. 20.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
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.🍋 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
23. 23.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) reading the message (d) writing the message
24. 24.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) whoever is fastest (d) the youngest child
25. 25.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
26. 26.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
27. 27.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) reading the message (d) ironing the paper
29. 29.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) a magnet (d) an adult with an iron
30. 30.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
31. 31.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
32. 32.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) writing the message (d) dipping the cotton bud
33. 33.True or false: writing the message is a job for an adult. (a) False (b) True
34. 34.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
35. 35.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
36. 36.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
37. 37.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
38. 38.⚖️ 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
39. 39.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
40. 40.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers

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