Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 907 · 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 kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the ironing time
3. 3.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, in the dark (d) yes, if cooled
4. 4.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
5. 5.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) plugging in the iron
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a small bowl (d) a cotton bud
7. 7.🛟 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
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a cotton bud (d) a mirror
9. 9.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
10. 10.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
14. 14.⚖️ 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
15. 15.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a mirror (c) yeast (d) an adult with an iron
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a small bowl (d) white paper
17. 17.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) putting the iron away
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a small bowl (d) a battery cell
19. 19.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
20. 20.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
21. 21.⚖️ 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
22. 22.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
24. 24.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
25. 25.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
26. 26.True or false: writing the message is a job for an adult. (a) False (b) True
27. 27.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a magnet
29. 29.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
30. 30.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
32. 32.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
33. 33.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
34. 34.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
35. 35.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
36. 36.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
37. 37.⚖️ 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
38. 38.⚖️ 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
39. 39.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) ironing the paper (d) letting the paper dry
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it

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