Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 624 · 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: a magnet is needed for the secret lemon message. (a) True (b) False
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the juice scorches first (d) the iron is brown
3. 3.⚖️ 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
5. 5.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) a magnet (d) a small bowl
7. 7.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a battery cell (d) a mirror
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
9. 9.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
10. 10.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
11. 11.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
12. 12.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a cotton bud (d) a balloon
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
17. 17.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
18. 18.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
19. 19.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) yeast (d) a balloon
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) it gets darker (d) the paper floats
21. 21.🛟 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
22. 22.True or false: ironing the paper is a job for an adult. (a) False (b) True
23. 23.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
27. 27.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) ironing the paper (d) cutting the lemon
28. 28.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) writing the message (d) putting the iron away
29. 29.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) yeast (d) a cotton bud
30. 30.⚖️ 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 measure it (c) we change it
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) turmeric powder
32. 32.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is magnetic (d) it is sticky
34. 34.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) plugging in the iron (d) writing the message
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: putting the iron away is a job for an adult. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the iron setting (c) how dark the writing is (d) the same paper
38. 38.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
39. 39.True or false: plugging in the iron is a job for an adult. (a) False (b) True
40. 40.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True

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